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 Post subject: 1275 head on 1100?
PostPosted: Tue Apr 10, 2007 7:01 pm 
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i was thinking of putting a 1275 head on tiny cause he's blown a headgasket aswell, i wanted to put on the 1275 head for a while but now im better off putting it on now that i need to do it anyway, is there anything i should know though, is it gonna cause the motor to run like crap? do i need to upgrade anything?

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PostPosted: Tue Apr 10, 2007 7:04 pm 
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You need to pocket the block to clear valves. It's quite a messy job if the engine is in car.

Done right, it's the best mod you can do to a smallbore. It's not often done, however, as it is very tricky.

Go get a 12G202 ported and have some big valves put in.

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PostPosted: Tue Apr 10, 2007 7:09 pm 
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sweet but what u mean but pocket the block?

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PostPosted: Tue Apr 10, 2007 7:11 pm 
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Slow-Po
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The search is your friend :wink: This thread is relatively fresh...

http://www.ausmini.com/forums/viewtopic ... +1100+head

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PostPosted: Tue Apr 10, 2007 7:13 pm 
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The combustion chamber on a 1275 head is lots shallower than a smallbore head. Also, exhaust valves hang over the side of the bore, lots with the 1275 head on a smallbore.
Pocketing, aka notching or flycutting puts a semi-circular recess on top of block, about 2.5mm deep, so the ex valves miss.
I can do it here properly with the mill, but not in the car... :lol:
it is just possible to fit a 1275 head without pocketing the block, provided that:
1. Cam lift is not high
2. exhaust seats in the head are sunk a bit
3. you never over-rev it. :wink:

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 Post subject:
PostPosted: Tue Apr 10, 2007 7:22 pm 
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hmmm its starting to sound like a pain in the ass lol cause now that the accident happen im thinking while im pulling off the manifolds to redo the head and gaskets i figured to do the dellotto carby and 1275 head, the car has extractors and a cam fitted already but juz wanted to know if it would be a good idea to change the head aswell or juz change the carby

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PostPosted: Tue Apr 10, 2007 7:36 pm 
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I'd do the carby, and mod the head you have already. :wink:

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 Post subject:
PostPosted: Tue Apr 10, 2007 8:02 pm 
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interesting... u reckon it will go as good as a 1275 head?

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PostPosted: Tue Apr 10, 2007 8:08 pm 
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High heel ninja
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If you read Graham Russell's article in mini experience, he is against putting 1275 heads on small motors, you can get a 202 or 206 head to work well on them, of course the 12G295 is not only the ultimate small bore head, but the ultimate mini head overall.

Doogie

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 Post subject:
PostPosted: Tue Apr 10, 2007 8:10 pm 
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so basicly work the 1100 and it will run better?

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PostPosted: Tue Apr 10, 2007 8:14 pm 
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If you read Keith Calvers stuff in Calver's Corner on MiniMania forum, he says a 1275 head is a great mod for a smallbore. Also he did a writeup recently on one in Mini/Miniworld? mag, with RE13 cam too.:lol:

I've done it both ways, both work well.
But plonking a 1275 head straight on without knowing what you're doing is a recipe for damage, so if I were U I'd mod a 202 head. :wink:

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 Post subject:
PostPosted: Tue Apr 10, 2007 8:16 pm 
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hmmm ok well i think tiny has a re13 cam in it im not 100% sure but i know he has some sort of cam lol and im guessing 202 head is an 1100s head?

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 Post subject:
PostPosted: Tue Apr 10, 2007 8:21 pm 
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12G202 head is a Morris 1100 or Mini 1100 head, NOT off a Morris 1100S. They are a 1275 motor, just to confuse you. :wink:

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:


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 Post subject:
PostPosted: Tue Apr 10, 2007 8:22 pm 
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lol ok well i could work the 1100 head but saying that i can also do the 1275 no probs, cause my tafe teacher builds motors for race cars and said he'd help if i wanted to do it juz dont know what would be better lol

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 Post subject:
PostPosted: Tue Apr 10, 2007 11:04 pm 
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Do you want to rebuild the whole engine? If you don't want to take it out or completely rebuild it, you only have one option, stick with a small bore head.

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